A rotogravure press has a printing cylinder with engraved ink wells on the surface. The cylinder rotates through an ink fountain or bath to fill the wells. A doctor blade scrapes excess ink from the cylinder surface. The web to be printed is directed to a pinch between the printing cylinder and an impression cylinder. The ink in the wells is transferred to the web in the pinch. The web typically travels at a high speed, drawing air, sometimes referred to as boundary layer air, with it. The ink has a volatile solvent which is picked up by the boundary layer air that strikes the cylinder surface between the doctor blade and pinch. The solvent laden air is dispersed in the press area, presenting a hazard to the press operators.
My U.S. Pat. application Ser. No. 317,759, filed Mar. 2, 1989, now U.S. Pat. No. 5,014,616, and assigned to the assignee of this application, discloses a scavenger mounted on the doctor blade table for exhausting solvent laden air from the press area.
This invention is concerned with a boundary layer air scraper which reduces the volume of air drawn to the printing cylinder by the moving web and thus reduces the capacity required in the scavenger.